From patchwork Wed Oct 21 08:56:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 11848687 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4292B14B2 for ; Wed, 21 Oct 2020 08:58:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18EE5223C7 for ; Wed, 21 Oct 2020 08:58:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="TASte01L" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502344AbgJUI63 (ORCPT ); Wed, 21 Oct 2020 04:58:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2441168AbgJUI5Q (ORCPT ); Wed, 21 Oct 2020 04:57:16 -0400 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6AFDFC0613CF for ; Wed, 21 Oct 2020 01:57:15 -0700 (PDT) Received: by mail-wr1-x444.google.com with SMTP id e17so2016679wru.12 for ; Wed, 21 Oct 2020 01:57:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=S+7ufuislqzXK0m1Ak/J4PVW8igwq369gehzbG0B91s=; b=TASte01LfK3tJrNEskEJg0JBrkEwFReNqZJcsPAqw0ud/54iE3NFZPYAz4seclzObY 8qyaNJ7feKdYZc7R1FFJdgR6e4chx6xmBKBCGr9MetZUB65nJ+IYSxcj8fXdkIxAF9Wa 835vPJ0u8wjGgm4Lqk1+pFbsMYj81cW6UvpFg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=S+7ufuislqzXK0m1Ak/J4PVW8igwq369gehzbG0B91s=; b=NDQ3+lBP705zz0yyiNUIrGsd9h7Wo1Gw3vAraV9IBEESNxeZyhOqjI7yuiA02jUWNc ZgRry2JnSiF/vriMQ2PmgFDLM/WM2I2NZ26iZh2HfD5stQXbUIYZGyMbB2QY3NSrpYHw MMPUFQQQBlJ3fog+rZI8/cw+aJKiwWVVgtfr/IJhTh7jREzXOP9xImjYA0NOkSIVfE2p C/fvMiGej4nBvP9gh+J6YKoEsGPfAe7pqSkzahGwBPwoJCNbTqRIBo5o9Fr7pcxCFd05 +WGTm/6SZHjUyP6Wyl6JzKYDxsx/TE0KiuhzcKrVyXYkZIIOxzTQskiWqMDBoXFb/bsT CbiQ== X-Gm-Message-State: AOAM532xJEFmJpn62HzD9U4UzXA9n6F5V6mJuELF+pwDDqmivp1SLOwK lUMPrTWpcLpZ++fTRf7xL6a7Ew== X-Google-Smtp-Source: ABdhPJzgdpJKzdh0Z7/Ixx6DmwTqWbM+l3YLKx7fvymTBFfXMek7eKSHLlh0kohA3cb0UMcaEODvqA== X-Received: by 2002:a5d:6a4f:: with SMTP id t15mr3390316wrw.126.1603270634157; Wed, 21 Oct 2020 01:57:14 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id q8sm2675939wro.32.2020.10.21.01.57.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Oct 2020 01:57:13 -0700 (PDT) From: Daniel Vetter To: DRI Development , LKML Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Daniel Vetter , Gerald Schaefer , Daniel Vetter , Jason Gunthorpe , Dan Williams , Kees Cook , Andrew Morton , John Hubbard , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Niklas Schnelle , Daniel Vetter Subject: [PATCH v3 08/16] s390/pci: Remove races against pte updates Date: Wed, 21 Oct 2020 10:56:47 +0200 Message-Id: <20201021085655.1192025-9-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201021085655.1192025-1-daniel.vetter@ffwll.ch> References: <20201021085655.1192025-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Way back it was a reasonable assumptions that iomem mappings never change the pfn range they point at. But this has changed: - gpu drivers dynamically manage their memory nowadays, invalidating ptes with unmap_mapping_range when buffers get moved - contiguous dma allocations have moved from dedicated carvetouts to cma regions. This means if we miss the unmap the pfn might contain pagecache or anon memory (well anything allocated with GFP_MOVEABLE) - even /dev/mem now invalidates mappings when the kernel requests that iomem region when CONFIG_IO_STRICT_DEVMEM is set, see commit 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims the region") Accessing pfns obtained from ptes without holding all the locks is therefore no longer a good idea. Fix this. Since zpci_memcpy_from|toio seems to not do anything nefarious with locks we just need to open code get_pfn and follow_pfn and make sure we drop the locks only after we're done. The write function also needs the copy_from_user move, since we can't take userspace faults while holding the mmap sem. v2: Move VM_IO | VM_PFNMAP checks around so they keep returning EINVAL like before (Gerard) v3: Polish commit message (Niklas) Reviewed-by: Gerald Schaefer Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Dan Williams Cc: Kees Cook Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Niklas Schnelle Cc: Gerald Schaefer Cc: linux-s390@vger.kernel.org Cc: Niklas Schnelle Signed-off-by: Daniel Vetter --- arch/s390/pci/pci_mmio.c | 98 +++++++++++++++++++++++----------------- 1 file changed, 57 insertions(+), 41 deletions(-) diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c index 401cf670a243..1a6adbc68ee8 100644 --- a/arch/s390/pci/pci_mmio.c +++ b/arch/s390/pci/pci_mmio.c @@ -119,33 +119,15 @@ static inline int __memcpy_toio_inuser(void __iomem *dst, return rc; } -static long get_pfn(unsigned long user_addr, unsigned long access, - unsigned long *pfn) -{ - struct vm_area_struct *vma; - long ret; - - mmap_read_lock(current->mm); - ret = -EINVAL; - vma = find_vma(current->mm, user_addr); - if (!vma) - goto out; - ret = -EACCES; - if (!(vma->vm_flags & access)) - goto out; - ret = follow_pfn(vma, user_addr, pfn); -out: - mmap_read_unlock(current->mm); - return ret; -} - SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr, const void __user *, user_buffer, size_t, length) { u8 local_buf[64]; void __iomem *io_addr; void *buf; - unsigned long pfn; + struct vm_area_struct *vma; + pte_t *ptep; + spinlock_t *ptl; long ret; if (!zpci_is_enabled()) @@ -158,7 +140,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr, * We only support write access to MIO capable devices if we are on * a MIO enabled system. Otherwise we would have to check for every * address if it is a special ZPCI_ADDR and would have to do - * a get_pfn() which we don't need for MIO capable devices. Currently + * a pfn lookup which we don't need for MIO capable devices. Currently * ISM devices are the only devices without MIO support and there is no * known need for accessing these from userspace. */ @@ -176,21 +158,37 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr, } else buf = local_buf; - ret = get_pfn(mmio_addr, VM_WRITE, &pfn); + ret = -EFAULT; + if (copy_from_user(buf, user_buffer, length)) + goto out_free; + + mmap_read_lock(current->mm); + ret = -EINVAL; + vma = find_vma(current->mm, mmio_addr); + if (!vma) + goto out_unlock_mmap; + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) + goto out_unlock_mmap; + ret = -EACCES; + if (!(vma->vm_flags & VM_WRITE)) + goto out_unlock_mmap; + + ret = follow_pte_pmd(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl); if (ret) - goto out; - io_addr = (void __iomem *)((pfn << PAGE_SHIFT) | + goto out_unlock_mmap; + + io_addr = (void __iomem *)((pte_pfn(*ptep) << PAGE_SHIFT) | (mmio_addr & ~PAGE_MASK)); - ret = -EFAULT; if ((unsigned long) io_addr < ZPCI_IOMAP_ADDR_BASE) - goto out; - - if (copy_from_user(buf, user_buffer, length)) - goto out; + goto out_unlock_pt; ret = zpci_memcpy_toio(io_addr, buf, length); -out: +out_unlock_pt: + pte_unmap_unlock(ptep, ptl); +out_unlock_mmap: + mmap_read_unlock(current->mm); +out_free: if (buf != local_buf) kfree(buf); return ret; @@ -274,7 +272,9 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr, u8 local_buf[64]; void __iomem *io_addr; void *buf; - unsigned long pfn; + struct vm_area_struct *vma; + pte_t *ptep; + spinlock_t *ptl; long ret; if (!zpci_is_enabled()) @@ -287,7 +287,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr, * We only support read access to MIO capable devices if we are on * a MIO enabled system. Otherwise we would have to check for every * address if it is a special ZPCI_ADDR and would have to do - * a get_pfn() which we don't need for MIO capable devices. Currently + * a pfn lookup which we don't need for MIO capable devices. Currently * ISM devices are the only devices without MIO support and there is no * known need for accessing these from userspace. */ @@ -306,22 +306,38 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr, buf = local_buf; } - ret = get_pfn(mmio_addr, VM_READ, &pfn); + mmap_read_lock(current->mm); + ret = -EINVAL; + vma = find_vma(current->mm, mmio_addr); + if (!vma) + goto out_unlock_mmap; + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) + goto out_unlock_mmap; + ret = -EACCES; + if (!(vma->vm_flags & VM_WRITE)) + goto out_unlock_mmap; + + ret = follow_pte_pmd(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl); if (ret) - goto out; - io_addr = (void __iomem *)((pfn << PAGE_SHIFT) | (mmio_addr & ~PAGE_MASK)); + goto out_unlock_mmap; + + io_addr = (void __iomem *)((pte_pfn(*ptep) << PAGE_SHIFT) | + (mmio_addr & ~PAGE_MASK)); if ((unsigned long) io_addr < ZPCI_IOMAP_ADDR_BASE) { ret = -EFAULT; - goto out; + goto out_unlock_pt; } ret = zpci_memcpy_fromio(buf, io_addr, length); - if (ret) - goto out; - if (copy_to_user(user_buffer, buf, length)) + +out_unlock_pt: + pte_unmap_unlock(ptep, ptl); +out_unlock_mmap: + mmap_read_unlock(current->mm); + + if (!ret && copy_to_user(user_buffer, buf, length)) ret = -EFAULT; -out: if (buf != local_buf) kfree(buf); return ret;